The effect of environmental conditions of the open channel period on the relative body condition of semianadromous burbot,Lota lota L. (Lotidae), in the Ob River

The results of long-term observations on changes in the relative body conditions of burbot (Lota lota L.) in the Lower Ob basin during the open channel period (June–September) are analyzed. Statistically significant strong positive dependence of the hepatosomatic index of spawners on the maximum flood level is revealed. An equation predicting the value of the hepatosomatic index of spawners from instrumentally measurable environmental parameters is constructed.     

The Dependence of the Duration of Downstream Migration of Burbot (Lota lota) Larvae on the Hepatosomatic Index of Spawners

Russian Journal of Ecology - This study estimates the dependence of the duration of the downstream migration of burbot larvae in the Voikar River (the Lower Ob basin) on the relative condition...     

Characteristics of parasitic infection in the least cisco, Coregonus sardinella valenciennes, 1848, in the Ural tributaries of the lower Ob

Data on the parasite fauna of the least cisco, Coregonus sardinella Valenciennes, 1848 in Ural tributaries of the Ob downstream of the city of Salekhard have been obtained for the first time. The formation patterns of the parasite fauna in this species and the rate (prevalence and intensity) of infection by Ichthyocotylurus erraticus (Odening, 1969), a parasite specific to coregonids, have been revealed. Infection of the least cisco with six parasite species (out of the 12 species found) occurs as the fish feed on zooplankton and benthic organisms. The dominant parasites are trematode larvae of the genera Ichthyocotylurus and, in some years, Diplostomum; this composition of dominants is evidence that the least cisco fattens up mainly in shallow areas. All sexually mature fish of this species were found to be infected by I. erraticus, but the average intensity of infection was rather low: the abundance index of the parasite did not exceed 40 ind. per fish. Analysis of the distribution of I. erraticus metacercariae in the least cisco shows that the relationship in the host-parasite system is stable and the parasite has no pathogenic effect on individuals of older age classes.     

Assessment of Changes in the Distance of Spawning Migrations of Semianadromous Burbot (Lota lota L., 1758) Spawners Based on Long-term Records of the Abundance of Downstream Migrating Larvae

Russian Journal of Ecology - The distance of spawning migrations of semianadromous burbot spawners is reconstructed based on long-term (2000–2017) records characterizing the contribution of...     

Ecological,morphological, and genetic diversity of burbot (<Emphasis Type="Italic">Lota lota</Emphasis> L., 1758) in large river basins of Western Siberia

A study has been performed on the ecological, morphological, and genetic diversity of burbot (sample size n = 204 and n = 134, respectively) from eight localities of the Ob–Irtysh and Taz river basins, Western Siberia. Fish differentiation in body size and weight depending on the dominant type of migration behavior, foraging conditions, and physiographic features of habitats has been revealed. A high genetic diversity (854-bp mtDNA control region) and a low level of between-sample differentiation is evidence for high intergroup gene flow.     

A Rationale for a Regional Network of Ecologically Valuable Areas

Several ecologically valuable objects identified on the basis of complex assessment and differentiation of the region are proposed for establishing a regional network of specially protected areas. To identify these objects, characteristics of the plant cover, soils, faunistic and hydrobiological associations, and landscapes have been analyzed using a 1 : 1000000 vegetation map. Five classes of ecologically valuable areas are distinguished according to the need for integrated protection of landscapes and their components or botanical and zoological objects. The concept has been realized using an example of the Khanty–Mansi Autonomous Area, Western Siberia.     

Influence of Hydrologic Conditions of the Lower Ob Floodplain on Reproduction in Coregonids

The influence of the water level in the period of the open river channel and the duration of lower floodplain inundation on the feeding conditions, abundance, and population state of coregonids in the Lower Ob was investigated. The long-term dynamics of catches of some coregonid species was analyzed and compared with changes in the hydrologic conditions in the floodplain. The relationship between basic hydrologic conditions in the Lower Ob (water level in the period of the open channel, the duration of the lower floodplain inundation), the coregonid population sizes, the state of spawners, and the size of catches is demonstrated.     

Trophic factor during the transition of peled (<Emphasis Type="Italic">Coregonus peled</Emphasis> Gmelin) larvae to active feeding in their native range

With regard to published data on the ecology of early peled larvae acclimated in lakes or reared under experimental or fish farm conditions, interannual variability of feeding and environmental conditions during the transition to exogenous feeding has been demonstrated for peled larvae in a control water body located in the floodplain of the main spawning tributary of the lower Ob River. The conditions that govern exogenous food consumption by early peled larvae and largely determine the fate of a given generation depend on both biotic (the concentration of food organisms) and abiotic factors (wind regime). The trophic optimum during the transition of larvae to exogenous feeding, which ensures the level of gut filling sufficient for their survival and growth in the control water body, is determined by a complex of natural events. The results of this study may be extrapolated to the entire native range of the Ob River peled population and used for planning the release of peled larvae into natural water bodies of Western Siberia to compensate for losses to their biological resources.     

Fine scale structure of convective mixed layer in ice-covered lake

Environmental Fluid Mechanics - Nonstationary convection forced by distributed buoyancy sources is a fundamental environmental fluid mechanics process, particularly in ice-covered freshwater...